Zoology and wildlife conservation

Female mate choice for large males in several species of seaweed fly (Diptera: Coelopidae)

Article Abstract:

It has been possible to establish the presence of female mate choice for large males in a number of species of coelopids from two genera, Coelopa and Gluma. Most of the species of coelopids do not have the alpha-beta inversion system previously believed to play a significant part in the evolution of female mate choice on the basis of male size in Coelopa frigida. It seems that female mate choice for large males evolved before the alpha-beta inversion system. The large-male mating advantage can clearly be maintained in the absence of the inversion system.

A study of the mating system of the seaweed fly, Coelopa ursina, revealed a positive relationship between the duration of premating struggles and male size and mating success. Large females were also found to reject males more easily than smaller females, suggesting that the premating struggle is not due to mate assessment by females. These findings suggest that sexual selection in the specie is a side-effect of sexual conflict.

The willingness of male seaweed flies, Coelopa frigida, to mate is not determined by female size. This indicates that male mate choice does not take place in seaweed flies. It also appears that male size has an impact on willingness to mate in some species, indicating that sexual selection favouring large males could be restricted because of counteracting selection on willingness to mate. Large males could benefit from increased longevity, while small males are more active.